We are assessing the extent of abnormal neuroendocrine function in major depressive disorders, as evidenced by abnormal hormonal responses to pharmacologic and physiologic stimuli and alterations in circadian patterns of hormone release. Studies include assessment in depressives and matched controls of circadian patterns of cortisol, HGH, and prolactin secretion; cortisol response to dexamethasone and atropine; diurnal hormonal responese to d-amphetamine, desipramine, and fenfluoramine; TSH response to TRH. Discriminatory power of differences between depressives and other groups are assessed for diagnostic potential, and the hormonal responses to neurotropic drugs are analyzed for implications for neurotransmitter mechanisms. Additionally, we are studying relation between prolactin secretion (as an index of dopamine blockade) and relapse rate in remitted schizophrenics maintained on very low neuroleptic dosage; hormonal and behavioral responses to amphetamine in typical schizophrenic compared to those in schizophrenics with histories of childhood asociality; and prolactin responses to parenteral haloperidol and dopamine in neuroleptic-resistant vs neuroleptic-responsive schizophrenics. Finally, we are studying responses of stress-sensitive hormones to lactate induced panic attacks, and to anticipatory anxiety in panic disorder cases, and control subjects.